Pipe-clamping assemblies are typically employed for the installation and joining of rigid pipes and pipe joints, particularly cast-iron pipes employed for sewage, sanitary and domestic plumbing requirements. The pipe-clamping assembly clamps together the pipe ends or joint ends in a fluid-tight-sealing, aligned relationship. The pipe-clamping assembly may be used on cast-iron pipes, polyvinyl-chloride pipes or steel pipes of various sizes and dimensions. A variety of pipe-clamping assemblies has been proposed, and in particular pipe-clamping assemblies as disclosed in U.S. Pat. No. 4,101,151, issued July 18, 1978 to Harry J. S. Ferguson, have provided a simple, easily manufactured, effective clamping assembly which provides for slight variations in external pipe diameters, which patent is hereby incorporated by reference.
The pipe-clamping assembly of the Ferguson patent comprises a flexible, typically sheet-metal clamping band of a defined length which is adapted to surround circumferentially the ends of the pipe or joints to be joined, and having an underlying, compressible, circumferential sealing gasket adapted to be disposed between the pipe or joint ends and the overlapping clamping bands, so as to overlap and bridge the junctions between the pipe or joint ends. Typically, the sealing gasket is characterized optionally by an outwardly raised central section which fits snugly within a raised central section of the band clamp, to prevent movement of the sealing gasket in the clamping position. Also, the sealing gasket generally comprises at least a plurality of interior, raised, generally parallel sealing beads on each side of the pipe or joint junctions, so that the sealing beads may engage the exterior surface of the pipe or joints in a sealing relationship, when the clamping assembly is in a clamping position. Further, the sealing gasket comprises an inwardly extending flap or sealing bead generally centrally positioned, against which the abutting edges of the pipe or joints are placed, which further holds the sealing gasket in position and forms a sealing relationship with the abutting ends of the pipe or joints. The clamping assembly also includes a means for tightening the clamping band, so as to compress and place the underlying sealing gasket into a fluid-tight sealing relationship. Typically, the clamping means comprises a pair of flat threadably moveable band straps on either side of the exterior of the clamping band.
A further improvement in the pipe clamp assembly of the Ferguson patent is described in U.S. Pat. No. 4,380,348, issued Apr. 19, 1983, to Frederick Swartz, also hereby incorporated by reference, which patent employs a similar sealing gasket, but which also discloses that the clamping band has an upwardly and reversely extending section along the edge, which section extends toward the underlying pipe or joint, to prevent unwanted outward movement of the sealing gasket in the clamping position.
Where the pipe ends or joint ends of different outside diameters are to be joined in a clamping assembly, which commonly arises in the joining of pipes or joints of different outside diameters and of different materials, such as copper, PVC, steel, cast iron and the like, in the plumbing field, it has been the practice to employ a sealing gasket for the clamping band which is specifically and integrally molded in one piece, wherein one or the other side of the gasket is formed, having a different selected inside diameter at the one end from the inside diameter of the other end, while the outside diameter of the sealing gasket is substantially the same, so that it may be placed beneath the clamping band. Specially molded, integral, transition gaskets for use with clamping assemblies have been prepared for common-pipe transition couplings, such as 2.times.11/2 inches or 4.times.3 inches; that is, a one-piece molded coupling has a diameter of the first number 2 or 4 inches at one end and 11/2 or 3 inches at the other end, thereby permitting the pipe or pipe joints of different sizes to be engaged within the clamping band. The internal surface of the relatively thin; that is, larger-diameter, end and the inside surface of the relatively large, that is, the smaller-diameter end have a pair of spaced-apart, raised beads which, like the sealing gasket, form a sealing relationship with the exterior surface of the different-diameter pipe or pipe joints to be joined. While such specially one-piece-molded transition gaskets are effective, they must be specially molded to fit the specific different pipe or joint ends and are, therefore, expensive. Furthermore, the plumber employing such molded gaskets has an inventory problem, since the gaskets are not interchangeable. Such one-piece-molded special gaskets are sold, for example, by Fernco, a joint-sealer company of Michigan, and Mission Clay Products Co. of California as replacement gaskets for the sealing gaskets, as set forth in the Ferguson and Swartz patents, supra.
Rubber pipe couplings for pressure pipe systems are also known, wherein a pipe has its external or outside diameter grooved and internal grooves in a rubber gasket which fit into the grooves on the outside of the pipe. Such pipe couplings are not for reduction purposes, but to provide for a high-pressure seal between the exterior surface of the pipe and an outside external housing, and typically are employed on pressurized water-sprinkler systems. Such high-pressure pipe couplings are known as Victaulic couplings and are sold by Victaulic Company of America of Easton, Pa.
It is desirable to provide an improved pipe-clamping assembly containing a removable and replaceable transition coupling therein and a transition coupling which is easy and simple to manufacture and to install, and which pipe-clamping system avoids the difficulties associated with one-piece, specially molded, expensive pipe gaskets.